A Russian physicist convicted of spying for China has been jailed for 14 years by a court in Siberia.

Valentin Danilov was cleared in 2003 of passing space secrets to China, but the result was later overturned.

Mr Danilov, 53, has always maintained that information he sold to China was already publicly available.

He is one of several Russian academics and journalists prosecuted by the internal security services, the FSB, on espionage charges.

Mr Danilov, a professor at Krasnoyarsk Technical University in Siberia, was first arrested in 2001.

He spent 19 months in prison before being cleared of charges in December 2003, but the verdict was overturned on appeal in December 2003.

A retrial in Krasnoyarsk returned a guilty verdict at the beginning of November.

Mr Danilov was sentenced by a judge in Krasnoyarsk and ordered to serve his sentence in a maximum security labour camp.

Appeal plans

Charges against Mr Danilov centred on alleged attempts to sell technology to China based on his work on the effects of the space environment on man-made satellites.

Russian authorities claimed his invention, a tool designed to examine ways to destroy redundant satellites, revealed state secrets.

I am a scientist. I have no links at all to weapons development programmes, or anything sensitive covered by the law on state secrets.

Valentin Danilov

He was charged with high treason and also accused of misappropriating funds from the university where he worked.

The case is the latest in a series of high-profile arrests and convictions of alleged spies.

Human rights groups have voiced concerns that the increase in convictions marks a return to Soviet-style scare tactics, correspondents say.

Mr Danilov's lawyer, Yelena Yevmenova, said she planned to launch an appeal against the sentence in the Russian Supreme Court, the Itar-Tass news agency reported.

The Supreme Court previously upheld the Krasnoyarsk prosecutor's appeal against the original guilty verdict, ordering Mr Danilov to stand trial a second time.

Danilov was accused of passing space secrets to China

In an interview with the BBC before being found guilty, Mr Danilov claimed his arrest set a dangerous precedent.

"I did no damage to this country. I am a scientist. I have no links at all to weapons development programmes, or anything sensitive covered by the law on state secrets. I don't know why they are being so stubborn," he said.

"If I can be found guilty of spying, then they could take any physicist here and make a case against him very easily."